Pump recoverer and preparation method thereof

Abstract

The invention provides a pumping recoverer and a preparation method thereof. According to the pumping recoverer, a plurality of pumping arms located in a second sub-part, an input signal optical fiber in the second sub-part and the second sub-part are prepared through a fused biconical taper process to obtain an optical fiber taper part; more pumping arms enable the residual pumping light to enter the output signal optical fiber from more directions and positions, so that the gain optical fiber can absorb the residual pumping light again, the overall pumping efficiency is improved, the residual pumping light is effectively utilized, and meanwhile, the optical fiber taper part is welded with the output signal optical fiber, so that the structure of the pumping recoverer is more compact, and the cost is reduced. And the number of connecting parts and interfaces between the optical fibers is reduced, so that low-loss transmission of optical signals is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular to a pump recoverer and a preparation method thereof. Background Art

[0002] High-power narrow-linewidth fiber lasers have a wide range of applications in gravitational wave detection, coherent communications, lidar, nonlinear frequency conversion, laser weapons, coherent beam combining, and spectral beam combining. In order to suppress nonlinear effects such as stimulated Brillouin scattering and stimulated Raman scattering in narrow-linewidth fiber lasers, the length of the laser gain fiber is usually shortened to increase the laser output power. In this case, the content of residual pump light in the laser will inevitably increase, resulting in a decrease in the laser conversion efficiency of the system; at the same time, the excess pump light will also increase the thermal load of the system, posing a hidden danger to the safety of the laser system.

[0003] There are two main ways to reduce the residual pump light in existing narrow linewidth fiber lasers. The first way is to increase the total pump absorption, improve the pump light conversion rate, and reduce the residual pump light content by designing a high-absorption gain fiber at the same fiber length; the second way is to recycle the pump light by interconnecting the pump arms of the combiner in the laser system structure. The first way requires the design of the ion doping concentration of the gain fiber, which is complex and may introduce new variables while increasing the absorption coefficient, such as mode instability effects to reduce the output power of the system; the second way requires the interconnection of the pump arms of the combiner, which introduces a new melting point. Fusion will cause a certain loss of laser efficiency, and the processing of the melting point will also increase the complexity of the system.

[0004] Therefore, there is an urgent need for a pump recovery device and a preparation method thereof to solve the above technical problems. Summary of the invention

[0005] The object of the present invention is to provide a pump recycler and a method for preparing the same, so as to improve the technical problem that it is difficult for a laser to recycle residual pump light in the prior art.

[0006] In order to solve the above technical problems, the present invention provides a pump recycler, comprising an input signal optical fiber, a plurality of pump optical fibers, an optical fiber holder, a quartz tube and an output signal optical fiber, wherein the pump arms of the plurality of pump optical fibers and the input signal optical fiber completely penetrate the optical fiber holder in the axial direction and are fixed in the quartz tube, and the quartz tube comprises a first sub-section and a second sub-section connected in the axial direction, wherein the first sub-section is arranged close to the optical fiber holder, and the second sub-section is arranged close to the output signal optical fiber; Among them, multiple pump arms located in the second sub-section, the input signal optical fiber in the second sub-section and the second sub-section are formed into an optical fiber taper through a fusion taper process; and one end of the optical fiber taper away from the optical fiber holder is fused with the output signal optical fiber.

[0007] Preferably, the optical fiber holder is any one of a honeycomb clamp and a multi-hole clamp; the optical fiber holder includes a first opening and a second opening, the first opening is located at the center of the optical fiber holder, and a plurality of second openings are arranged around the first opening, and the plurality of second openings are parallel to the central axis of the first opening.

[0008] Preferably, the input signal optical fiber completely passes through the first opening along the axial direction, and the pump arm completely passes through the second opening along the axial direction; The two pump arms of the same pump fiber are symmetrical about the input signal fiber.

[0009] Preferably, the diameter of the inner wall of the quartz tube is larger than the sum of the cladding diameters of the two pump arms and the input signal optical fiber; the input signal optical fiber in the quartz tube is gap-matched with the adjacent multiple pump arms, and the multiple pump arms are gap-matched with the inner wall of the quartz tube.

[0010] Preferably, the input signal fiber and the output signal fiber are both double-clad passive fibers or double-clad polarization-maintaining passive fibers, and the operating bands of the input signal fiber and the output signal fiber include any one of the 1.0µm band, the 1.5µm band and the 2.0µm band.

[0011] Accordingly, the present invention also provides a method for preparing the pump recovery device as described above, the method comprising the following steps: S10, completely passing the pump arms of the plurality of pump optical fibers and the input signal optical fibers through the optical fiber holder along the axial direction and fixing them in the quartz tube; S20, performing a melt taper process on the pump arm inserted into the quartz tube, a portion of the input signal optical fiber inserted into the quartz tube, and a portion of the quartz tube to obtain an optical fiber taper; S30, cutting a portion of the optical fiber taper, placing an end of the optical fiber taper away from the optical fiber holder axially opposite to the output signal optical fiber and fusing the end to the output signal optical fiber.

[0012] Preferably, in step S10, before inserting the pump arm and the input signal optical fiber into the quartz tube, the method further includes: removing coating layers of the pump arm and the input signal optical fiber respectively.

[0013] Preferably, after removing the coating layer of the pump arm and before inserting the pump arm into the quartz tube, the method further comprises: performing a taper process on the pump arm to reduce the cladding diameter of the pump arm.

[0014] Preferably, after removing the coating layer of the input signal optical fiber and before inserting the input signal optical fiber into the quartz tube, the method further includes: performing cladding corrosion treatment on the input signal optical fiber, wherein the cladding corrosion method is hydrofluoric acid treatment.

[0015] Preferably, in step S30: the cutting angle of the tapered portion of the optical fiber is within 1.5°.

[0016] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides a pump recoverer and a preparation method thereof, wherein the pump recoverer obtains a fiber taper by melting and taper-drawing a plurality of pump arms in the second sub-section, an input signal fiber in the second sub-section, and the second sub-section, more pump arms enable the remaining pump light in the laser system to enter the output signal fiber from more directions and positions, thereby improving the overall pumping efficiency and effectively utilizing the remaining pump light. At the same time, the fiber taper is fused with the output signal fiber, making the structure of the pump recoverer more compact, reducing the number of connecting components and interfaces between optical fibers, and thus achieving low-loss transmission of optical signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the radial structure of a pump recovery device provided in an embodiment of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of the optical fiber holder in the pump recovery device provided in an embodiment of the present invention; Figure 3 is a flow chart of a method for preparing a pump recovery device provided by an embodiment of the present invention; Figure 4 It is a radial schematic diagram before the taper step in the method for preparing a pump recovery device provided by an embodiment of the present invention; Figure 5 It is a schematic axial cross-sectional view of a taper step in a method for preparing a pump recovery device provided by an embodiment of the present invention; Figure 6 It is a radial schematic diagram of a welding step in a method for preparing a pump recycler provided in an embodiment of the present invention; In the attached drawings: 100 - pump recycler; 10 - pump optical fiber; 11 - pump arm; 20 - input signal optical fiber; 30 - optical fiber holder; 31 - first opening; 32 - second opening; 40 - quartz tube; 41 - optical fiber taper; 50 - output signal optical fiber. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The purpose of the present invention is to provide a pump recycler to improve the pump recovery rate by increasing the number of pump optical fibers in view of the defects of the prior art. The present invention utilizes the double arms of the pump optical fiber to recover the remaining pump light, which can reduce the optimization of the gain optical fiber length or doping concentration or the processing of the optical device in the fiber laser system; increasing the number of pump optical fibers can improve the pump recovery rate.

[0020] The technical solution of the present invention is now described in conjunction with specific embodiments.

[0021] See also Figure 1 , Figure 1 is a schematic diagram of the radial structure of the pump recycler 100 provided in an embodiment of the present invention; specifically, the pump recycler 100 comprises an input signal optical fiber 20, a plurality of pump optical fibers 10, an optical fiber holder 30, a quartz tube 40 and an output signal optical fiber 50, and the pump arms 11 of the plurality of pump optical fibers 10 and the input signal optical fiber 20 completely penetrate the optical fiber holder 30 in the axial direction and are fixed in the quartz tube 40; The quartz tube 40 includes a first sub-section and a second sub-section connected along the axial direction, the first sub-section is arranged close to the optical fiber holder 30, and the second sub-section is arranged close to the output signal optical fiber 50; Among them, multiple pump arms 11 located in the second sub-section, the input signal optical fiber 20 in the second sub-section and the second sub-section are formed into an optical fiber taper 41 through a fusion taper process; the end of the optical fiber taper 41 away from the optical fiber holder is fused with the output signal optical fiber 50.

[0022] In the embodiment of the present invention, the input signal optical fiber 20 is used to externally seed the seed light source, and then transmits it in the structure inside the pump recycler 100, and subsequently cooperates with other components to realize the functions of related processing and transmission of optical signals.

[0023] In an embodiment of the present invention, a plurality of pump fibers 10 are used to introduce the remaining pump light in the laser system into the pump recycler 100, and provide energy support for the gain fiber again, such as participating in related processes such as optical amplification, to help improve the related performance of the optical signal.

[0024] Figure 2 It is a schematic diagram of the three-dimensional structure of the optical fiber holder 30 in the pump recoverer 100 provided in an embodiment of the present invention; wherein, the optical fiber holder 30 includes a first opening 31 and a second opening 32, the first opening 31 is located at the center of the optical fiber holder 30, and a plurality of second openings 32 are arranged around the first opening 31, and the central axis of the plurality of second openings 32 and the first opening 31 are parallel to each other.

[0025] Specifically, the optical fiber holder 30 is any one of a honeycomb clamp and a porous clamp; wherein the optical fiber holder 30 plays a role in fixing and limiting the input signal optical fiber 20 and the pump optical fiber 10, ensuring that they are in accurate positions before subsequent operations such as being loaded into the quartz tube 40, ensuring the regularity of the entire structure and the rationality of the relative position relationship between the optical fibers, which is very important for the effective coupling of light.

[0026] Specifically, the input signal fiber 20 completely penetrates the first opening 31 along the axial direction, and the pump arm 11 completely penetrates the second opening 32 along the axial direction; the two pump arms 11 of the same pump fiber 10 are symmetrical with the input signal fiber 20 as the axis.

[0027] Furthermore, the input signal optical fiber 20 completely passes through the first opening 31 of the optical fiber holder 30 along the axial direction. Such a design can accurately determine the position of the input signal optical fiber 20 in the entire pump recycler 100 structure, thereby preventing the input signal optical fiber 20 from being offset or shaken during subsequent assembly and use. Because the first opening 31 is located at the center of the optical fiber holder 30, the input signal optical fiber 20 is located at the core of the entire optical fiber layout.

[0028] Furthermore, the pump arm 11 completely penetrates the corresponding second opening 32 along the axial direction, and a plurality of second openings 32 are arranged around the first opening 31, so that the pump arm 11 of the pump fiber 10 is spatially arranged in an orderly manner around the input signal fiber 20. This orderly layout is very critical for the pump light to enter the system and interact with the signal light. It is conducive to achieving efficient coupling of the pump light to the input signal fiber 20. When the pump light is transmitted from the pump arm 11, since each pump arm 11 has a clear and reasonable positional relationship, the pump light can be relatively uniformly and accurately converged to the input signal fiber 20 located in the center, reducing the problems of pump light dispersion and low coupling efficiency that may be caused by disordered arrangement. For example, if the pump arm 11 is placed randomly, the propagation direction of the pump light will be chaotic, and it is difficult to ensure that enough pump light can effectively enter the input signal fiber 20 to provide energy for the signal light or participate in related optical processes. The orderly layout formed by penetrating the second opening 32 can solve this problem well.

[0029] Furthermore, the two pump arms 11 of the same pump fiber 10 are designed to be symmetrical with the input signal fiber 20 as the axis. From the perspective of light field distribution, the pump light can form a relatively uniform light field around the input signal fiber 20. If the two pump arms 11 are asymmetrical, the intensity of the pump light on one side may be much higher than that on the other side, resulting in a significant imbalance in the light field around the input signal fiber 20, which is not conducive to the processing of optical signals and the stability of the entire system. At the same time, this symmetrical setting also plays a balancing role. When the pump light provides energy to the gain medium to amplify the signal light, the uniform light field distribution can ensure that the gain medium at each position can absorb the pump light energy more evenly, avoiding the situation of local excess or insufficient energy.

[0030] In the embodiment of the present invention, the quartz tube 40 includes a first sub-section and a second sub-section connected along the axial direction, the first sub-section is arranged close to the optical fiber holder 30, and the second sub-section is arranged close to the output signal optical fiber 50; In the embodiment of the present invention, the quartz tube 40 provides physical support and protection for the internal optical fibers (including the input signal optical fiber 20, the pump optical fiber 10, etc.) on the one hand, and is also involved in the preparation process of the optical fiber taper 41 on the other hand. Its structural characteristics affect the formation of the optical fiber taper 41 and the subsequent transmission of light therein.

[0031] Specifically, a through hole is provided in the quartz tube 40 along the axial direction, the pump arms 11 at both ends of the pump optical fiber 10 are located on the inner periphery of the quartz tube 40, and the input signal optical fiber 20 is located at the center of the quartz tube 40; wherein, a through hole is provided in the quartz tube 40 along the axial direction, and the existence of this through hole provides space and positioning guidance for the placement of the optical fiber. It enables the optical fiber to pass through the quartz tube 40 in an orderly manner along the axial direction, ensuring that each optical fiber is in a relatively fixed and accurate position in the quartz tube 40, which is crucial for the subsequent stable operation of the entire pump recycler 100 and the effective transmission of light therein.

[0032] Furthermore, the pump arm 11 of the pump optical fiber 10 is arranged on the inner periphery of the quartz tube 40, surrounding the input signal optical fiber 20 located in the center, so that the pump light can converge to the input signal optical fiber 20 from multiple directions. Such a layout is firstly conducive to improving the coupling efficiency of the pump light to the input signal optical fiber 20, allowing more pump light to effectively enter the input signal optical fiber 20, and providing sufficient energy support for subsequent optical signal processing (such as optical amplification and other processes); secondly, the annular distribution of the pump arm 11 around the input signal optical fiber 20 helps to create a relatively uniform light field environment around the input signal optical fiber 20; thirdly, such a fixed position relationship enables each optical fiber to form an orderly and compact layout in the quartz tube 40, and when it is subjected to a certain degree of vibration, due to the clear layout of each optical fiber and the limiting effect of the quartz tube 40, it can still maintain a normal optical transmission state, ensuring that the pump recycler 100 continuously and stably performs its functions of recovering pump light and processing optical signals.

[0033] Specifically, the diameter of the inner wall of the quartz tube 40 is larger than the sum of the cladding diameters of the two pump arms 11 and the input signal optical fiber 20; this size design provides the necessary space margin for placing the input signal optical fiber 20 and the pump optical fiber 10 in the quartz tube 40. It ensures that the input signal optical fiber 20 and the pump optical fiber 10 can be smoothly loaded into the quartz tube 40, avoiding the difficulty in installing the input signal optical fiber 20 and the pump optical fiber 10 due to too narrow space, and even the possibility of squeezing and damaging the input signal optical fiber 20 and the pump optical fiber 10, thereby affecting the performance of the input signal optical fiber 20 and the pump optical fiber 10 and the subsequent light transmission.

[0034] Specifically, the input signal optical fiber 20 in the quartz tube 40 is gap-matched with the adjacent multiple pump arms 11, which means that there is a certain small gap between them, rather than being tightly fitted together. From an optical point of view, the existence of the gap is conducive to reducing the optical interference that may be caused by direct contact between optical fibers.

[0035] Specifically, the multiple pump arms 11 and the inner wall of the quartz tube 40 are also clearance-fitted, which facilitates the installation and positioning of the pump arms 11 in the quartz tube 40, so that the pump arms 11 can easily penetrate the quartz tube 40 along the axial direction and be in a suitable position, avoiding damage to the pump arms 11 that may be caused by interference fit (i.e., the outer diameter of the pump arms 11 is almost equal to or even slightly larger than the inner diameter of the quartz tube 40, and it needs to be forcibly squeezed into the tube during installation), and ensuring the integrity of the pump arm 11 structure and its function of transmitting pump light. On the other hand, the existence of the gap also reserves space for the possible thermal expansion and contraction of the quartz tube 40 and the pump arm 11. Under different working environment temperatures, the thermal expansion coefficients of the materials of the quartz tube 40 and the pump arm 11 are different. If there is no gap, the two may squeeze each other when the temperature changes, destroying the optical fiber structure or changing the original position relationship of the optical fiber, affecting the normal transmission of light and the stability of the system, and the gap fit can effectively avoid the occurrence of such problems.

[0036] In the embodiment of the present invention, the input signal fiber 20 and the output signal fiber 50 are both double-clad passive fibers or double-clad polarization-maintaining passive fibers, and the working bands of the input signal fiber 20 and the output signal fiber 50 include any one of the 1.0µm band, the 1.5µm band, and the 2.0µm band. Among them, for the pump recycler 100, its input signal fiber 20 and the output signal fiber 50 have such multi-band applicability, which greatly enhances the compatibility of the entire device with different light sources, different optical devices, and different application systems.

[0037] See also Figure 3 The present invention also provides a method for preparing the pump recovery device 100 as described above, the method comprising the following steps: S10 , the pump arms 11 of the plurality of pump optical fibers 10 and the input signal optical fibers 20 are completely passed through the optical fiber holder 30 along the axial direction and fixed in the quartz tube 40 .

[0038] Specifically, step S10 also includes: See also Figure 1 , Figure 2 as well as Figure 4 , remove the coating of the pump arms 11 at both ends of N pump optical fibers 10 (N≥1) and insert them into the optical fiber holder 30, remove the coating of the input signal optical fiber 20 and insert it into the center of the optical fiber holder 30, and insert the pump arms 11 at both ends of the pump optical fiber 10 and the input signal optical fiber 20 into the quartz tube 40 for fixation.

[0039] In one embodiment, three pump fibers 10 are selected, and a portion of the coating layer is removed from the ends of the pump arms 11 and the input signal fibers 20 at both ends of the pump fibers 10. Before the pump arms 11 and the input signal fibers 20 at both ends of the pump fibers 10 are inserted into the quartz tube 40 for fixation, the pump arms 11 at both ends of the pump fibers 10 are tapered to reduce the cladding diameter, and the input signal fibers 20 are clad and etched. The etching method includes but is not limited to hydrofluoric acid treatment.

[0040] Specifically, by removing the coating layer of the pump arm 11, the pump light can be transmitted more smoothly from the pump arm 11 to the relevant area, and the input signal optical fiber 20 can more effectively interact with other optical fibers for optical signals, thereby reducing problems such as signal attenuation and low coupling efficiency caused by the presence of the coating layer.

[0041] Specifically, the taper process will change the structure of the pump arm 11, making its cladding diameter smaller. This can adjust the optical field distribution of the pump light in the pump arm 11, so that the light is more concentrated near the core, and the energy density of the pump light is increased, which helps the subsequent pump light to be more efficiently coupled into the input signal fiber 20 or to transfer energy with other areas that need the action of the pump light. On the other hand, when the pump arm 11 with a reduced cladding diameter is subsequently melt-tapered with other optical fibers, it can better match the structure and optical field characteristics of other optical fibers, further optimize the transmission and coupling effect of light in the entire system, and enhance the optical correlation and collaborative working ability between the optical fibers.

[0042] Specifically, the input signal optical fiber 20 is subjected to cladding corrosion treatment, and the corrosion method includes but is not limited to hydrofluoric acid treatment. Hydrofluoric acid can chemically react with the optical fiber cladding material (usually silica, etc.), selectively remove a portion of the cladding material, thereby adjusting the cladding thickness or structure. In the process of fusion taper, the core of the input signal optical fiber 20 after cladding corrosion will be less affected during taper, which can effectively reduce the change of the signal optical fiber core during the taper process, thereby reducing signal insertion loss and mode distortion, ensuring that the signal light is transmitted in the optical fiber in a more stable and efficient manner, and better achieves optical coupling and other interactions with other optical fibers.

[0043] S20 , performing a melt taper process on the pump arm 11 inserted into the quartz tube 40 , a portion of the input signal optical fiber 20 inserted into the quartz tube 40 , and a portion of the quartz tube 40 to obtain an optical fiber taper portion 41 .

[0044] Specifically, step S20 also includes: See also Figure 1 , Figure 2 , Figure 4 as well as Figure 5The pump arms 11 at both ends of the fixed pump optical fiber 10, the input signal optical fiber 20 and the quartz tube 40 are melt-tapered to form an optical fiber taper 41; the melt-tapering methods for the optical fiber bundle include but are not limited to hydrogen-oxygen flame taper, graphite taper, laser taper and electrode taper.

[0045] Specifically, the fusion taper process is to change the structure of the optical fiber to optimize the transmission and coupling of light in the optical fiber. The optical fiber is softened by heating and then stretched to form a fiber taper 41. This process can adjust the diameter, refractive index distribution, and light field mode of the optical fiber. For example, in the pump recycler 100, the tapered optical fiber can better couple the pump light and the signal light, thereby improving the transmission efficiency of light. At the same time, the pump arms 11 at both ends of the pump optical fiber 10, the input signal optical fiber 20, and the quartz tube 40 are tapered together, so that their structures can change synchronously, thereby forming an integral environment that is conducive to light interaction in the fiber taper 41. The quartz tube 40 can stabilize the optical fiber structure during the taper process, and the change in its own shape also helps to optimize the light field distribution.

[0046] S30 , cutting a portion of the optical fiber taper 41 , and making one end of the optical fiber taper 41 away from the optical fiber holder 30 axially opposite to the output signal optical fiber 50 and fusion-splicing the end with the output signal optical fiber 50 .

[0047] Specifically, step S30 also includes: See also Figure 6 , Figure 6 It is a radial schematic diagram of the fusion step in the preparation method of the pump recycler 100 provided in an embodiment of the present invention, and the above steps include: first, radially cutting a portion of the optical fiber taper 41 so that the cutting angle of the optical fiber taper 41 is within 1.5°; second, selecting an output signal optical fiber 50, the core size of the output signal optical fiber 50 matches the core size of the input signal optical fiber 20, and the cladding size of the output signal optical fiber 50 matches the size of the quartz tube 40 after taper; third, removing the coating layer at the end of the output signal optical fiber 50, and cutting it so that the cutting angle is within 1.5°; finally, the end of the optical fiber taper 41 away from the optical fiber holder 30 is axially opposite to the output signal optical fiber 50 and fused with the output signal optical fiber 50.

[0048] Specifically, a cutting angle of 1.5° helps to maintain the optical field matching between the optical fiber taper 41 and the output signal optical fiber 50. If the cutting angle is not appropriate, it will cause a sudden change in the optical field mode, increasing the possibility of light transmission loss and mode distortion. For example, during the fusion process, a cutting angle that is too large may lead to low optical coupling efficiency at the fusion point, affecting the performance of the entire pump recycler 100.

[0049] The pump recycler 100 and the preparation method thereof provided in the embodiment of the present invention can improve the reuse rate of pump light and achieve the effect of pump recovery by increasing the number of pump optical fibers 10. At the same time, since the cladding of the input signal optical fiber 20 is corroded before the fusion taper, the change of the signal optical fiber core during the taper process is weakened, thereby reducing the signal insertion loss and mode distortion.

[0050] Specifically, when the number of pump optical fibers 10 is increased, it means that there are more channels to introduce pump light into the optical system used by the pump recycler 100. For example, when there is only one pump optical fiber 10, the pump light power that can be input per unit time is limited, and the absorption of the pump light by the gain medium in the system is often difficult to achieve complete, and there will always be some pump light that is not fully utilized and remains. As the number of pump optical fibers 10 increases, the total pump light input power increases accordingly. Even if the absorption efficiency is maintained at a certain level, the total amount of residual pump light that is not absorbed will increase. The design purpose of the pump recycler 100 is to collect these residual pump lights and reuse them, so more residual pump lights provide more "raw materials" for recycling and reuse, thereby improving the reuse rate of pump light and better achieving the effect of pump recovery.

[0051] Furthermore, a higher pump light reuse rate has a positive impact on the entire optical system. It can compensate for the problem of insufficient pump light utilization caused by factors such as the shortened gain fiber length to a certain extent, allowing the system to obtain more available pump light energy without adding too many complex designs (such as changing the gain fiber doping concentration, etc.), which helps to increase the laser output power and the overall light conversion efficiency of the system, and reduces the negative effects such as increased system thermal load caused by excessive residual pump light, ensuring a more stable and efficient operation of the system.

[0052] The present invention provides a pump recycler 100 and a preparation method thereof to recycle the residual pump light in the laser system. By increasing the number of pump optical fibers 10, the pump light recycle rate can be improved. At the same time, since the cladding of the input signal optical fiber 20 is etched before the fusion taper, the change of the signal optical fiber core during the taper process is weakened, and the signal insertion loss and mode distortion are reduced. It has the advantages of simple structure and reliable performance.

[0053] Of course, the above is only a preferred embodiment of the present case, and there may be more variations in specific applications. For example, the number of pump fibers 10 of the above-mentioned pump recycler 100 is 3. In theory, the number of pump fibers 10 only needs to be greater than or equal to 1. As the number of pump fibers 10 increases, the pump recovery rate will increase.

[0054] In summary, the present invention provides a pump recycler 100 and a preparation method thereof, and connects the pump recycler 100 to a narrow linewidth fiber laser system, so as to effectively reuse the residual pump light in the laser. By increasing the number of pump arms 11, the pump recovery rate can be effectively improved. There is no need to increase the length of the gain fiber or to design a complex gain ion distribution to increase the absorption rate of the pump light, nor is there any need to increase the absorption rate of the pump light by adding a combiner and fusing the pump arms or a side pump combiner and other complex operations or devices. This solution can simply and efficiently realize the reuse of the residual pump light in the laser.

[0055] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference may be made to the description in other embodiments.

[0056] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A pump recovery device, characterized in that: The invention comprises an input signal optical fiber, a plurality of pump optical fibers, an optical fiber holder, a quartz tube and an output signal optical fiber, wherein the pump arms of the plurality of pump optical fibers and the input signal optical fiber all penetrate the optical fiber holder in the axial direction and are fixed in the quartz tube, and the quartz tube comprises a first sub-section and a second sub-section connected in the axial direction, wherein the first sub-section is arranged close to the optical fiber holder, and the second sub-section is arranged close to the output signal optical fiber; Among them, the plurality of pump arms located in the second sub-section, the input signal optical fiber in the second sub-section and the second sub-section are formed into an optical fiber taper through a fusion taper process; and the end of the optical fiber taper away from the optical fiber holder is fused with the output signal optical fiber.

2. The pump recovery device according to claim 1, characterized in that: The optical fiber holder is any one of a honeycomb clamp and a multi-hole clamp; the optical fiber holder includes a first opening and a second opening, the first opening is located at the center of the optical fiber holder, a plurality of the second openings are arranged around the first opening, and the plurality of the second openings are parallel to the central axis of the first opening.

3. The pump recovery device according to claim 1, characterized in that: The input signal optical fiber completely passes through the first opening along the axial direction, and the pump arm completely passes through the second opening along the axial direction; Wherein, the two pump arms of the same pump optical fiber are symmetrical with respect to the input signal optical fiber.

4. The pump recovery device according to claim 1, characterized in that: The diameter of the inner wall of the quartz tube is greater than the sum of the cladding diameters of the two pump arms and the input signal optical fiber; the input signal optical fiber located in the quartz tube is gap-matched with the multiple adjacent pump arms, and the multiple pump arms are gap-matched with the inner wall of the quartz tube.

5. The pump recovery device according to claim 1, characterized in that: The input signal optical fiber and the output signal optical fiber are both double-clad passive optical fibers or double-clad polarization-maintaining passive optical fibers, and the operating bands of the input signal optical fiber and the output signal optical fiber include any one of the 1.0µm band, the 1.5µm band and the 2.0µm band.

6. A method for preparing a pump recovery device according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: S10, completely passing the pump arms of the plurality of pump optical fibers and the input signal optical fiber through the optical fiber holder along the axial direction and fixing them in the quartz tube; S20, performing a melt taper process on the pump arm inserted into the quartz tube, a portion of the input signal optical fiber inserted into the quartz tube, and a portion of the quartz tube to obtain the optical fiber taper; S30, cutting a portion of the optical fiber taper, placing an end of the optical fiber taper away from the optical fiber holder axially opposite to the output signal optical fiber and fusing the end to the output signal optical fiber.

7. The method for preparing a pump recovery device according to claim 6, characterized in that: In the step S10, before inserting the pump arm and the input signal optical fiber into the quartz tube, the method further includes: removing coating layers of the pump arm and the input signal optical fiber respectively.

8. The method for preparing a pump recovery device according to claim 7, characterized in that: After removing the coating layer of the pump arm and before inserting the pump arm into the quartz tube, the method further includes: performing a taper process on the pump arm to reduce the cladding diameter of the pump arm.

9. The method for preparing a pump recovery device according to claim 7, characterized in that: After removing the coating layer of the input signal optical fiber and before inserting the input signal optical fiber into the quartz tube, the method further includes: performing cladding corrosion treatment on the input signal optical fiber, wherein the cladding corrosion method is hydrofluoric acid treatment.

10. The method for preparing a pump recovery device according to claim 6, characterized in that: In the step S30: the cutting angle of the tapered portion of the optical fiber is within 1.5°.

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